Internal combustion engines are commonly used to power small watercraft such as personal watercraft. These watercraft include a hull which defines an engine compartment. The engine is positioned in the engine compartment. The output shaft of the engine is coupled to a water propulsion device of the watercraft, such as an impeller.
Air must be supplied to the engine from outside the hull for use in the combustion process. Typically, air flows through one or more ducts in the hull into the engine compartment, and then through an intake system of the engine to the combustion chamber(s) thereof.
The intake system commonly includes an air intake into which air from within the engine compartment is drawn. This air then flows through an intake pipe to the combustion chamber(s) of the engine.
Fuel is also supplied to the engine for use in the combustion process. In order to accurately meter the fuel and improve engine operating efficiency and performance, the fuel is injected into the combustion chambers with one or more fuel injectors. In this arrangement, fuel is supplied to the fuel injector at high pressure. Each injector has an electrically operated valve which selectively opens and closes, controlling the flow of fuel therethrough to the engine.
The amount of fuel to be injected in order to achieve optimum performance is partially dependent on the density of air also entering the combustion chamber. For this reason, at least one air temperature sensor may be used to provide air temperature data for use in calculating the density of the air entering the combustion chamber so that the amount of fuel injected by the fuel injector(s) may be adjusted accordingly.
One problem associated with this arrangement is that water may contact the air temperature sensor and damage it. In particular, water often flows with the air through the intake ducts into the engine compartment. This water may directly flow onto the sensor, or pool in the bottom of the hull and splash about due to the pitching and rocking movement of the watercraft as it moves through the water. When the water sprays or splashes onto the air temperature sensor, it may interfere with the accurate operation of the sensor, and even corrode the sensor and interrupt the electrical signal flowing therefrom, preventing the signal from communicating with the fuel injector.
An improved air temperature sensor arrangement for an engine powering a watercraft is desired.